ALLEVIATION OF DROUGHT STRESS IN PHASEOLUS VULGARIS L. CULTIVARS USING BIOSTIMULANTS IN ORGANIC AGRICULTURE

This research was conducted to investigate the effects of phytostimulators application (Messenger, Crop-Set, ISR-2000) on yield and morphological parameters of common bean cultivars grown under four irrigation regimes [25% (I25), 50% (I50), 75% (I75) and 100% (I100)]. Phytostimulators reversed the negative effect of drought on plant growth. Significant interaction was determined for all parameters except stem diameter and stomatal conductivity between phytostimulator and drought applications. The best effect on stomatal conductivity was provided from ISR-2000 (23.5% reduction) application. The highest yield was obtained from the 25% water deficiency applied with 1.91 ton per hectare. It was determined that the best results were obtained from Messenger in Efsane and Asya cultivars and ISR-2000 in the Öz Ayşe cultivar on yield. Therefore, it was concluded that the use of phytostimulators under drought stress is important for the effective use of water.

The Application of a Commercially Available Citrus-Based Extract Mitigates Moderate NaCl-Stress in Arabidopsis thaliana Plants

Aims: The aim of this study was to assess the effect of BC204 as a plant biostimulant on Arabidopsis thaliana plants under normal and NaCl-stressed conditions. Methods: For this study, ex vitro and in vitro growth experiments were conducted to assess the effect of both NaCl and BC204 on basic physiological parameters such as biomass, chlorophyll, proline, malondialdehyde, stomatal conductivity, Fv/Fm and the expression of four NaCl-responsive genes. Results: This study provides preliminary evidence that BC204 mitigates salt stress in Arabidopsis thaliana. BC204 treatment increased chlorophyll content, fresh and dry weights, whilst reducing proline, anthocyanin and malondialdehyde content in the presence of 10 dS·m−1 electroconductivity (EC) salt stress. Stomatal conductivity was also reduced by BC204 and NaCl in source leaves. In addition, BC204 had a significant effect on the expression of salinity-related genes, stimulating the expression of salinity-related genes RD29A and SOS1 independently of NaCl-stress. Conclusions: BC204 stimulated plant growth under normal growth conditions by increasing above-ground shoot tissue and root and shoot growth in vitro. BC204 also increased chlorophyll content while reducing stomatal conductivity. BC204 furthermore mitigated moderate to severe salt stress (10–20 dS·m−1) in A. thaliana. Under salt stress conditions, BC204 reduced the levels of proline, anthocyanin and malondialdehyde. The exact mechanism by which this occurs is unknown, but the results in this study suggest that BC204 may act as a priming agent, stimulating the expression of genes such as SOS1 and RD29A.

SILICON NUTRITION IN ALLEVIATING SALT STRESS IN APPLE PLANT

Salinity is one of the major environmental stresses that adversely affect fruit yield and quality. Thus, finding an effective way of ameliorating salinity damage is important for sustainable fruit production. Silicon (Si) treatment effectively counteracts the effects of many abiotic stress factors such as salinity, drought, cold, iron deficiency. To probe into the potential alleviating salinity malignant effects, we investigated the protective roles of Si. An apple plant (Malus domestica Borkh.) cv. ‘Fuji’ grafted on M9 clonal rootstock was chosen for the experiment and imposed to salinity stress for 4 months with 35 mM NaCl. Si with different three doses (0.5, 1 ve 2 mM) was applied to the roots of the salt-stressed apple plants except control. Si treatments inhibited apple plants growth depression through increasing stomatal conductivity, chlorophyll and decreasing electrolyte leakage. 0.5 mM Si improved root:shoot dry weight under salinity condition. The lowest values of membrane permeability were found in 0.5 and 2 mM Si treatments (21.45 and 21.55%, respectively) while salt had the highest value (48.43%). Salt exhibited a rapid decrease in stomatal conductivity by 49% compared to the control. We hypothesis that Si treatment contributed to cell walls, involving membrane stabilizing and fortification. Our findings showed that Si increased apple plant tolerance against salinity.

Nutritional status and physiological parameters of maize cultivated with sewage sludge

ABSTRACT The use of sewage sludge as a source of nutrients and organic matter for agricultural soils is a well-established practice. However, few reports highlight the effect of the nutrients and potentially toxic elements provided by organic wastes application on the plant physiological parameters, such as photosynthetic activity and stomatal conductivity. We performed a greenhouse experiment with maize exposed to a dystrophic red Latosol amended with mineral fertilizer and different rates of sewage sludge with the following objectives: i) assess the nutrients and metal uptake translocation and distribution in plants and ii) evaluate the relationship between plant physiological parameters and yield indicators under the study conditions. The application of sewage sludge increased the soil organic matter, pH, and the amounts of available Ca, S, and Mg, comparing to the mineral fertilizer treatment. The plants promote a higher translocation of macronutrients to the shoots in the sewage sludge treatments, which results in higher photosynthetic activity, stomatal conductivity, and maize yield parameters. Moreover, the trace elements, which can cause toxicity in small concentrations, were founded mainly in the roots, which indicates a plant defense mechanism.

Pengaruh Cekaman Air Terhadap Karakter Fisiologis Tembakau Temanggung dan Kaitannya dengan Hasil dan Kadar Nikotin Rajangan Kering

<p>Tembakau temanggung ditanam pada akhir musim penghujan sehingga sering mengalami cekaman air dan berakibat pada penurunan hasil dan kadar nikotin rajangan kering. Penelitian bertujuan untuk mengetahui pengaruh cekaman air terhadap karakter fisiologis tembakau temanggung serta kaitannya dengan hasil dan kadar nikotin rajangan kering. Penelitian dilakukan di rumah kaca Balittas Malang pada Maret–Oktober 2010 dengan menggunakan Rancangan Petak Terbagi dan diulang 3 kali. Petak utama terdiri atas 3 jenis tanah yakni Komplek Eutrudepts-Hapludalfs, Komplek Dystrudepts-Hapludalfs, dan Vitraquands. Anak petak terdiri atas 5 tingkat kelembapan tanah (60, 70, 80, 90, dan 100% dari kapasitas lapangan). Hasil penelitian me-nunjukkan bahwa cekaman air pada tiga jenis tanah berpengaruh negatif terhadap konduktivitas stomata, laju fotosintesis, hasil dan kadar nikotin rajangan kering, serta berpengaruh positif terhadap bobot spesifik daun. Pengaruh cekaman air terhadap hasil rajangan kering terjadi melalui penurunan konduktivitas stomata dan laju fotosintesis selama fase setelah pemangkasan. Pengaruh cekaman air terhadap kadar nikotin terjadi me-lalui penurunan konduktivitas stomata sebelum pembungaan dan setelah pemangkasan, penurunan laju fotosintesis setelah pemangkasan, dan peningkatan bobot spesifik daun setelah pemangkasan.</p><p> </p><p>Temanggung tobacco is grown at the end of wet season which so often experience water stress. Water stress can decrease dry slice yield and nicotine content. The study was aimed to determine the effect of water stress on physiological characteristics of temanggung tobacco and its relation to dry slice yield and nicotine content. Research was conducted in greenhouse of Indonesian Sweetener and Fibre Crops Research Institute, Malang from March to October 2010 using splitplot design and repeated three times. The main plot consisted of three types of soil (Complex Eutrudepts-Hapludalfs, Complex Dystrudepts-Hapludalfs, and Vitraquands). The Subplot consisted of five soil moisture levels (60, 70, 80, 90, and 100% of field capacity). The results showed that water stress on the third series of the soil negatively affect stomatal conductivity, the photosynthesis rate, dry slice yield and nicotine content, as well as the positive effect on specific leaf weight. Effect of water stress on dry slice yield occurred through the decrease of stomata conductivity and photosynthetic rate during the phase after topping. The effect of water stress on nicotine content occurred through a reduction in stomatal conductivity before flowering and after topping, decrease of photosynthetic rate after topping, and increase of specific leaf weight after topping.</p>

Exogenous 5-Aminolevulenic Acid Promotes Antioxidative Defence System, Photosynthesis and Growth in Soybean against Cold Stress

In the present study, the possibility of enhancing cold stress tolerance of young soybean plants (Glycine max [L.] Merr) by exogenous application of 5-aminolevulinic acid (ALA) was investigated. ALA was applied at various concentrations (0, 0.3, 0.6 and 0.9 mM) by seed priming and foliar application method. After ALA treatment, the plants were subjected to cold stress at 10 ± 0.5 °C for 72 h. Cold stress significantly decreased plant growth, relative water content, chlorophyll, photosynthesis and stomatal conductivity, while it increased electrolyte leakage and proline accumulation. ALA at low concentrations (0.3 mM) protected plants against cold stress, enhancing plant height, shoot fresh and dry weight, chlorophyll content, photosynthesis, stomatal conductivity as well as relative water content. Increase of electrolyte leakage was also prevented by 0.6 mM ALA. ALA also enhanced superoxide dismutase and catalase activities at 0.6 mM concentration especially under cold stress conditions. Proline increased with increasing in ALA concentration under both temperature conditions. In most cases, application of ALA by spraying method was better than seed priming method. Results showed that ALA, which is considered as an endogenous plant growth regulator, can be used effectively to protect soybean plants from the damaging effects of cold stress, by enhancing the activity of antioxidative enzymes, protecting cell membrane against reactive oxygen species and finally by promoting chlorophyll synthesis, leading to more intense photosynthesis and more carbon fixation, without any adverse effect on the plant growth.